According to the Papua New Guinea Department of Mining (DOM), reports coming from Bialla Local Level Government (LLG) indicated that Bamus showed signs of unusual activity. At 1010 on 12 July 2006 observers saw white vapor coming out at the summit. The emission was forceful at about 1110 that day, with a tint of gray color in the emission. The vapor-rich plume blew inland to the SSE. No ashfall was reported.

Officials from Bialla LLG together with a DOM observer witnessed the activity, as did Max Benjamin from Walindi Resort (~ 40-50 km away). Benjamin called the Rabaul Volcano Observatory to report the activity. No satellite-detected thermal anomalies at the volcano were reported by the MODIS website for this time frame.

Information is preliminary and subject to change. All times are local (unless otherwise noted)

"Strong seismicity took place near Bamus during February. The seismicity started on the 2nd when almost 100 events were recorded (maximum ML 5.8 [but see 15:3]). In the following days the activity waned, but began to increase on the 8th. Seismicity peaked between the 10th and the 15th, when ~1,400 events were recorded, including three earthquakes of M 5.8-6.0. Activity declined irregularly during the following 10 days, but began increasing again on the 25th. During the second peak of activity, between the 25th and the 28th, ~880 events were recorded including two earthquakes of M 5.0. Activity declined again at the end of the month.

"Inspections of Bamus were carried out on 13 and 16 February. Rockfalls had occurred at many places on the volcano, apparently associated with the seismicity. Temperatures in solfataric areas on the summit tholoid remained low (<15°C) however. A temporary seismograph network, operated in the area between 13 and 16 February, enabled locations of some earthquakes to be calculated. Epicenters were distributed in a 10-km-long NNE-trending zone that included the S flanks of Bamus. Focal depths ranged between 0 and 23 km. The seismicity was continuing in early March and was being monitored primarily by the permanent seismograph at Ulawun Volcano."

"Seismicity. . . continued throughout March, although at a milder level after the 5th. Following intense February seismicity that involved 83 earthquakes of ML >=4.0, eight of ML >=5.0, and one of ML >=6.0, activity was strong again 3-5 March. More than 720 earthquakes (two of ML = 5.0-5.1 and 10 of ML >=4.5) were recorded before seismicity decreased to 20-50 events/day of small-moderate magnitude. The energy released by the February-March seismicity was relatively large, 1.22 x 1021 ergs (figure 1).

Figure 1. Daily number of earthquakes (bars) and cumulative energy release (circles) near Bamus, February-March 1990. Magnitudes (ML) of larger events are given over earthquake count bars. Courtesy of RVO.

"An inspection of the Bamus area was carried out on 6 March. Rockfalls had occurred at many places on the volcano and in the limestone ranges to the S. However, no change was observed in the temperatures of the solfataric areas on the summit tholoid (which remained at <=15°C).

"Temporary seismograph networks were operated in the area 13-16 February and 6-8 March. Earthquake locations defined a broad 15-km-long seismic zone trending NNE that extended from the Nakanai Mountains to the S flank of Bamus (figure 2). Within this zone was a concentration of locations trending ENE near the S foot of Bamus. Earthquake focal depths ranged from 0 to 23 km.

Figure 2. Epicenters of seismic events at Bamus, 13-16 February and 6-8 March 1990. Courtesy of RVO.

"Cross-sections . . . (figure 3) suggest that the main cluster of earthquakes defines an ENE-trending near-vertical fault. This orientation is consistent with the structural pattern evident in the Miocene limestone immediately S of, and underlying, Bamus.

"The cause of this seismicity remains uncertain. Its ongoing fluctuating character, and the fact that its swarms include but do not occur in response to larger earthquakes, could be consistent with magmatic injection. On the other hand, ML 5-6 earthquakes are uncommon for magmatic events. Analysis of the magnitude/frequency distribution of the earthquakes shows that the 'b' value is ~1, which is indicative of tectonic earthquake sequences. The seismicity was continuing in early April and was being monitored primarily by the permananent seismograph at Ulawun."

"Seismic activity . . . decreased markedly in April. Following a period of intense activity in early March, the frequency of occurrence and magnitude of earthquakes decreased gradually, with only 27 events of ML >=3 recorded in April (from a total of 200 events picked up by the Ulawun station, 25 km away). Event frequency ranged between 2 and 7/day. Two isolated earthquakes of ML 5.6 and 4.2 occurred on the 26th."

According to the Papua New Guinea Department of Mining (DOM), reports coming from Bialla Local Level Government (LLG) indicated that Bamus showed signs of unusual activity. At 1010 on 12 July 2006 observers saw white vapor coming out at the summit. The emission was forceful at about 1110 that day, with a tint of gray color in the emission. The vapor-rich plume blew inland to the SSE. No ashfall was reported.

Officials from Bialla LLG together with a DOM observer witnessed the activity, as did Max Benjamin from Walindi Resort (~ 40-50 km away). Benjamin called the Rabaul Volcano Observatory to report the activity. No satellite-detected thermal anomalies at the volcano were reported by the MODIS website for this time frame.

Basic Data

Volcano Types

Rock Types

Major
Andesite / Basaltic Andesite

Tectonic Setting

Subduction zoneContinental crust (> 25 km)

Population

Within 5 kmWithin 10 kmWithin 30 kmWithin 100 km

50
630
19,320
71,997

Geological Summary

Symmetrical 2248-m-high Bamus volcano, also referred to locally as the South Son, is located SW of Ulawun volcano, known as the Father. These two volcanoes are the highest in the 1000-km-long Bismarck volcanic arc. The andesitic stratovolcano is draped by rainforest and contains a breached summit crater filled with a lava dome. A satellitic cone is located on the southern flank, and a prominent 1.5-km-wide crater with two small adjacent cones is situated halfway up the SE flank. Young pyroclastic-flow deposits are found on the volcano's flanks, and villagers describe an eruption that took place during the late 19th century.

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Synonyms

South Son | Sudsohn

Photo Gallery

The symmetrical basaltic and andesitic Ulawun stratovolcano is one of Papua New Guinea's most frequently active. Ulawun and Bamus volcano (upper left) are the two highest volcanoes of the Bismarck arc, and are known as the Father and South Son volcanoes, respectively. The upper 1000 m of the 2334-m-high Ulawun is unvegetated. The peak to the left of the summit is a prominent E-W-trending escarpment on the south side that may result from large-scale slumping. Historical eruptions date back to the beginning of the 18th century.

Photo by Wally Johnson (Australia Bureau of Mineral Resources).

Symmetrical 2248-m-high Bamus volcano, also referred to as South Son, is seen here from the NE beyond the upper slopes of Ulawun volcano, known as the Father. These two volcanoes are the highest in the 1000-km-long Bismarck volcanic arc. Bamus stratovolcano is draped by rainforest and contains a breached summit crater filled with a lava dome. A satellitic cone is located on the southern flank, and a prominent 1.5-km-wide crater with two small adjacent cones is situated halfway up the SE flank.

WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.

EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).

Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.

Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.